"If it passes, it won't change North Carolina's law on marriage," he said in a message sponsored by the Coalition to Protect North Carolina Families. "What it will change is North Carolina's ability to keep good businesses, attract new jobs and attract and keep talented entrepreneurs."

A survey of 1,026 likely Democratic and Republican primary voters showed North Carolinians look poised to pass the amendment.

Raleigh-based Public Policy Polling found 55 percent of those questioned on May 5-6 supported the amendment banning gay marriage and civil unions while 39 percent opposed it. The poll had a margin of error of plus or minus 3.1 percent.

Twenty-eight states have voter-approved constitutional bans on same-sex marriages, according to the National Conference of State Legislatures.